Optimization of Sorbents to remove dissolved 137Cs and Risk Assessment of Secondary Contamination
Abstract
There are many safety measures to prevent accidents at nuclear power plants, but unexpected situations can occur that cause severe radiation accidents. From these accidents, radionuclides will be released into the surrounding area, and 137Cs, a highly soluble radionuclide, can contaminate water resources. In this situation, sorbents can be used to remove dissolved 137Cs, and it is important to evaluate 137Cs-removal effectiveness of sorbents. We determined the optimal size of several sorbents by comparing the settling time and adsorption time. Additionally, the risk assessment for secondary contamination in the aquifer was conducted by simulating the 137Cs transport.
In this study, three kinds of sorbents were considered to remove dissolved 137Cs: illite, zeolite and activated carbon. First, the settling time was evaluated depending on the physical properties (e.g., diameter, shape, and roughness) of sorbents. Then, the adsorption time was calculated from the equilibrium adsorption experiments between sorbents and 137Cs. After that, the optimal size of sorbent particles having maximum 137Cs-removal efficiency was derived according to the lake depth. The secondary contamination of desorbed 137Cs can be affected by the desorption rate, the amount of 137Cs in sorbents, and hydrogeologic properties of the aquifer. Therefore, using EOS7R of TOUGH2 module which can consider the decay rate and adsorption of chemicals in the aquifer medium, 2D transport simulation was conducted. As a result, the risk of desorbed 137Cs from deposited sorbents was not large because of the high distribution coefficient of 137Cs. However, to predict more precisely, it is necessary to consider the realistic situation such as a heterogeneous reservoir, fractured bedrock, and colloid-facilitated transport. - This research was supported by Basic Science Research Project through the Korea Environmental Industry Technology Institute (KEITI) funded by the Ministry of Environment (Grant Number: 2018002440003)- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H21I1851L
- Keywords:
-
- 1829 Groundwater hydrology;
- HYDROLOGY;
- 1831 Groundwater quality;
- HYDROLOGY;
- 1832 Groundwater transport;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY